This invention relates to the use of quaternized polyamidoamines in the preventing, breaking or resolving of emulsions of the water-in-oil type as well as oil-in-water type emulsions.
Most naturally occurring emulsions of petroleum oil and water take the form of water-in-oil emulsions in which the oil is a continuous phase and tiny drops of water are dispersed in the oil. Occasionally, however, oil-in-water emulsions are encountered either in the production, handling or refining of petroleum oil or fractions thereof. Unfortunately, in both types of emulsions, the emulsions are often extremely stable and will not resolve after standing for long periods. While such emulsions often occur naturally, such emulsions may also occur artificially resulting from one or more of numerous operations encountered in various industries. For example, such emulsions may be obtained from producing wells as a result of enhanced oil recovery methods or from the bottom of crude oil storage tanks. Other such oil-in-water emulsions include steam cylinder emulsions, wax-hexane-water emulsions, butadiene-tar-in-water emulsions, emulsions of flux oil and steam condensate, styrene-in-water emulsions and synthetic latex-in-water emulsions. In all instances, it is generally desirable to resolve the emulsion in order the the oil phase may be separated from the water phase.
Historically, such emulsions have been resolved or broken by contacting the emulsion with a chemical demulsifying agent, thereby causing the emulsions of resolve and stratify into its component phases of water and oil or brine and oil after the emulsion has been allowed to stand in a relatively quiescent state. In another type of demulsification, the emulsion contains substantial quantities of salt in the aqueous phase and it is necessary to carry out a desalting operation prior to further refinement of the oil phase in order to prevent the accumulation of large deposits of salt in the refining apparatus. In such desalting operations, it is common to employ a chemical demulsifying agent in a manner similar to that mentioned hereinbefore. A wide variety of chemical demulsifying agents has been employed in this manner in the past. For example, such demulsifying agents include oxyalkylated condensation products obtained by reacting phenols, formaldehydes and alkylene polyamines as disclosed in U.S. Pat. No. 3,166,516; ultra high molecular weight ethylenically unsaturated polymers, polyalkylene oxylene polymers, polyesters, polyamides, polymer of ketenes and the like as described in U.S. Pat. No. 3,557,017; amidoamine polymers as described in U.S. Pat. No. 3,528,928; as well as other chemicals such as sulfonates, oxyalkylated amines, oxyalkylated alkylphenols, oxyalkylated alcohols and the like. While each of the foregoing and other conventional demulsifiers are effective in some emulsions, it is found that many are not as effective as desired, particularly in resolving emulsions derived from steam recovery of heavy crudes by processes typical of some of the California oil fields.
Accordingly, it is highly desirable to provide a demulsification process for resolving emulsions of such heavy crudes as well as other oil-in-water emulsions and the like.